[PATCH 27/27] ext4: introduce a mount option for iomap buffered I/O path

Zhang Yi
2024-10-22T03:13:09Z

From: Zhang Yi <yi.zhang@huawei.com>

Introduce the buffered_iomap and the nobuffered_iomap mount options to
enable the iomap buffered I/O path for regular files. This option is
currently disabled by default until we can support more comprehensive
features along this path.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
---
fs/ext4/ext4.h | 1 +
fs/ext4/inode.c | 2 ++
fs/ext4/super.c | 7 +++++++
3 files changed, 10 insertions(+)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 0096191b454c..c2a44530e026 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1257,6 +1257,7 @@ struct ext4_inode_info {
* scanning in mballoc
*/
#define EXT4_MOUNT2_ABORT 0x00000100 /* Abort filesystem */
+#define EXT4_MOUNT2_BUFFERED_IOMAP 0x00000200 /* Use iomap for buffered IO */

#define clear_opt(sb, opt) EXT4_SB(sb)->s_mount_opt &= \
~EXT4_MOUNT_##opt
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 97abc88e6658..b6e041a423f9 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5153,6 +5153,8 @@ bool ext4_should_use_buffered_iomap(struct inode *inode)
{
struct super_block *sb = inode->i_sb;

+ if (!test_opt2(sb, BUFFERED_IOMAP))
+ return false;
if (ext4_has_feature_inline_data(sb))
return false;
if (ext4_has_feature_verity(sb))
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 89955081c4fe..435a866359d9 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1675,6 +1675,7 @@ enum {
Opt_discard, Opt_nodiscard, Opt_init_itable, Opt_noinit_itable,
Opt_max_dir_size_kb, Opt_nojournal_checksum, Opt_nombcache,
Opt_no_prefetch_block_bitmaps, Opt_mb_optimize_scan,
+ Opt_buffered_iomap, Opt_nobuffered_iomap,
Opt_errors, Opt_data, Opt_data_err, Opt_jqfmt, Opt_dax_type,
#ifdef CONFIG_EXT4_DEBUG
Opt_fc_debug_max_replay, Opt_fc_debug_force
@@ -1806,6 +1807,8 @@ static const struct fs_parameter_spec ext4_param_specs[] = {
fsparam_flag("no_prefetch_block_bitmaps",
Opt_no_prefetch_block_bitmaps),
fsparam_s32("mb_optimize_scan", Opt_mb_optimize_scan),
+ fsparam_flag("buffered_iomap", Opt_buffered_iomap),
+ fsparam_flag("nobuffered_iomap", Opt_nobuffered_iomap),
fsparam_string("check", Opt_removed), /* mount option from ext2/3 */
fsparam_flag("nocheck", Opt_removed), /* mount option from ext2/3 */
fsparam_flag("reservation", Opt_removed), /* mount option from ext2/3 */
@@ -1900,6 +1903,10 @@ static const struct mount_opts {
{Opt_nombcache, EXT4_MOUNT_NO_MBCACHE, MOPT_SET},
{Opt_no_prefetch_block_bitmaps, EXT4_MOUNT_NO_PREFETCH_BLOCK_BITMAPS,
MOPT_SET},
+ {Opt_buffered_iomap, EXT4_MOUNT2_BUFFERED_IOMAP,
+ MOPT_SET | MOPT_2 | MOPT_EXT4_ONLY},
+ {Opt_nobuffered_iomap, EXT4_MOUNT2_BUFFERED_IOMAP,
+ MOPT_CLEAR | MOPT_2 | MOPT_EXT4_ONLY},
#ifdef CONFIG_EXT4_DEBUG
{Opt_fc_debug_force, EXT4_MOUNT2_JOURNAL_FAST_COMMIT,
MOPT_SET | MOPT_2 | MOPT_EXT4_ONLY},
--
2.46.1